HEX is a complicated mining algorithm which is comprised of 16 different algorithms; same as X16R (Raven mining). The 16 different algorithms that make up HEX are: BLAKE / BMW / GROESTL / JH / KECCAK / SKEIN / LUFFA / CUBEHASH / SHAVITE / SIMD / ECHO / HAMSI / FUGUE / SHABAL / WHIRLPOOL / SHA2. The difference between X16R and HEX is the sequences of these 16 algorithm varies. Not just that; in X16R there are only 16 possible scenarios to solve a block but HEX has got more than 18 quadrillion scenarios and due to this unpredictable variation , construction of ASIC becomes difficult.